Electrochemical treatment of human urine for its storage and reuse as flush water

Ikematsu, Mineo; Kaneda, Kazuhiro; Iseki, Masahiro; Yasuda, Masashi

doi:10.1016/j.scitotenv.2007.03.028

Cited by 44 publications

(26 citation statements)

References 9 publications

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“…The presence of reactive chlorine species (RCS), even with a trace concentration, would inhibit the activity of the enzyme urease. 2 In addition, the RCS was found to interfere in the spectrometric urea analysis by diacetylmonoxime. 3 The color generation by the reagent addition appeared to increase with the electrolysis time.…”

Section: S3mentioning

confidence: 99%

Urea Degradation by Electrochemically Generated Reactive Chlorine Species: Products and Reaction Pathways

Cho

Hoffmann

2014

Environ. Sci. Technol.

125

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This study investigated the transformation of urea by electrochemically generated reactive chlorine species (RCS). Solutions of urea with chloride ions were electrolyzed using a bismuth doped TiO2 (BiO x /TiO2) anode coupled with a stainless steel cathode at applied anodic potentials (E a) of either +2.2 V or +3.0 V versus the normal hydrogen electrode. In NaCl solution, the current efficiency of RCS generation was near 30% at both potentials. In divided cell experiments, the pseudo-first-order rate of total nitrogen decay was an order of magnitude higher at E a of +3.0 V than at +2.2 V, presumably because dichlorine radical (Cl2 –·) ions facilitate the urea transformation primary driven by free chlorine. Quadrupole mass spectrometer analysis of the reactor headspace revealed that N2 and CO2 are the primary gaseous products of the oxidation of urea, whose urea-N was completely transformed into N2 (91%) and NO3 – (9%). The higher reaction selectivity with respect to N2 production can be ascribed to a low operational ratio of free available chlorine to N. The mass-balance analysis recovered urea-C as CO2 at 77%, while CO generation most likely accounts for the residual carbon. In light of these results, we propose a reaction mechanism involving chloramines and chloramides as reaction intermediates, where the initial chlorination is the rate-determining step in the overall sequence of reactions.

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Section: S3mentioning

confidence: 99%

Urea Degradation by Electrochemically Generated Reactive Chlorine Species: Products and Reaction Pathways

Cho

Hoffmann

2014

Environ. Sci. Technol.

125

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“…Recent research has demonstrated that electrochemistry offers an attractive alternative to the above-mentioned traditional methods for treating wastewaters [16][17][18][19][20][21][22]. Electrochemical coagulation, which is one of these techniques, is the electrochemical production of destabilization agents that brings about charge neutralization for pollutant removal, and it has been used for water or wastewater treatment.…”

Section: Introductionmentioning

confidence: 99%

Removal of iron from drinking water by electrocoagulation: Adsorption and kinetics studies

Vasudevan

Jayaraj

Lakshmi

et al. 2009

Korean J. Chem. Eng.

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The present study provides an electrocoagulation process for the removal of iron from drinking water with aluminum alloy as the anode and stainless steel as the cathode. The studies were carried out as a function of pH, temperature and current density. The adsorption capacity was evaluated with both the Langmuir and the Freundlich isotherm models. The results showed that the maximum removal efficiency of 98.8% was achieved at a current density of 0.06 A dm −2 , at a pH of 6.5. The adsorption of iron preferably fitting the Langmuir adsorption isotherm suggests monolayer coverage of adsorbed molecules. The adsorption process follows second-order kinetics. Temperature studies showed that adsorption was endothermic and spontaneous in nature.

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“…It can be expressed as u=ð1 À uÞ e À2au ¼ k C e (24) where u ¼ q e /q m , q e is the adsorption capacity in equilibrium (mg/g) and q m is the theoretical monolayer saturation capacity (mg/g). The linearized form is given as…”

Section: Frumkin Equationmentioning

confidence: 99%

“…Electrochemically generated metallic ions from these electrodes undergo hydrolysis near the anode to produce a series of activated intermediates that are able to destabilize the finely dispersed particles present in the water and waste water to be treated. The advantages of electrocoagulation include high particulate removal efficiency, a compact treatment facility, relatively low cost, and the possibility of complete automation [19][20][21][22][23][24]. This technique does not require supplementary addition of chemicals and reduces the volume of produced sludge.…”

Section: Introductionmentioning

confidence: 99%

Studies on the Removal of Arsenate by Electrochemical Coagulation Using Aluminum Alloy Anode

Vasudevan

Lakshmi

Sozhan

2010

CLEAN Soil Air Water

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The removal of arsenate from aqueous solution was carried out by electrochemical coagulation using aluminum alloy as anode and stainless steel as cathode. Various operating parameters on the removal efficiency of arsenate were investigated, such as initial arsenate ion concentration, initial pH, current density, and temperature. Effect of coexisting anions such as silicate, fluoride, phosphate, and carbonate were studied on the removal efficiency of arsenate. The optimum removal efficiency of 98.4% was achieved at a current density of 0.2 A/dm 2 at a pH of 7.0. The experimental data were tested against different adsorption isotherm models for describing the electrochemical coagulation process. The adsorption of arsenate preferably fitting the Langmuir adsorption isotherm suggests monolayer coverage of adsorbed molecules. First and second order rate equations were applied to study adsorption kinetics. The adsorption process follows second order kinetics model with good correlation. Temperature studies showed that adsorption was endothermic and spontaneous in nature.

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Electrochemical treatment of human urine for its storage and reuse as flush water

Cited by 44 publications

References 9 publications

Urea Degradation by Electrochemically Generated Reactive Chlorine Species: Products and Reaction Pathways

Urea Degradation by Electrochemically Generated Reactive Chlorine Species: Products and Reaction Pathways

Removal of iron from drinking water by electrocoagulation: Adsorption and kinetics studies

Studies on the Removal of Arsenate by Electrochemical Coagulation Using Aluminum Alloy Anode

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